Genome-wide association for plasma urea concentration in sheep

Urea-related traits can be used as an indicator of nitrogen (N) utilization and excretion and have a key role in the protein metabolism of ruminants. A genome-wide association study (GWAS) was carried out for plasma urea concentration (PUC) in Santa Ines sheep. PUC was recorded in 229 lambs, which were also genotyped with OvineSNP50K BeadChip. After data quality control, 43,996 variants and 229 PUC records were used in GWAS. The WssGBLUP method was used in GWAS analysis and genome windows of 1.0 Mb were analyzed. Estimate of heritability for PUC was 0.10 +/- 0.07. Seven genomic regions in the chromosomes OAR3, OAR6, OAR10, OAR23, and OAR24 explained 12.4% of the additive genetic variance and harbored 95 genes. Some candidate genes (LOC114113767, LOC105612842 in OAR3, CLOCK and NMU in OAR6, KLHL1, and NBEA in OAR10, NDUFV2, RAB31, and RAB12 in OAR23, AZGP1, LAMTOR4, SMURF1, ARPC1A, ARPC1B, LOC101110727, LOC101110202, and CYP3A24 in OAR24) were found. Moreover, five significant (P < 0.05) pathways (steroid hormone biosynthesis, linoleic acid metabolism, retinol metabolism, chemical carcinogenesis, and endocytosis) were identified. Future studies can identify the potential use of the variants in these genes to improve performance and health of sheep, as well as to identify association with N utilization and excretion.

Automated summary

GWAS was conducted on plasma urea concentration in Santa Ines sheep, identifying several genomic regions, candidate genes, and significant pathways that could potentially be used to improve performance and health of sheep and understand nitrogen utilization and excretion.